;-----------------------------------------------------------------
;
; TCP_output
;
; IN: eax = socket pointer
;
; OUT: /
;
;-----------------------------------------------------------------
align 4
TCP_output:
DEBUGF 1,"TCP_output, socket: %x\n", eax
; We'll detect the length of the data to be transmitted, and flags to be used
; If there is some data, or any critical controls to send (SYN / RST), then transmit
; Otherwise, investigate further
mov ebx, [eax + TCP_SOCKET.SND_MAX]
cmp ebx, [eax + TCP_SOCKET.SND_UNA]
jne .not_idle
mov ebx, [eax + TCP_SOCKET.t_idle]
cmp ebx, [eax + TCP_SOCKET.t_rxtcur]
jle .not_idle
; We have been idle for a while and no ACKS are expected to clock out any data we send..
; Slow start to get ack "clock" running again.
mov ebx, [eax + TCP_SOCKET.t_maxseg]
mov [eax + TCP_SOCKET.SND_CWND], ebx
.not_idle:
.again:
mov ebx, [eax + TCP_SOCKET.SND_NXT] ; calculate offset (71)
sub ebx, [eax + TCP_SOCKET.SND_UNA] ;
mov ecx, [eax + TCP_SOCKET.SND_WND] ; determine window
cmp ecx, [eax + TCP_SOCKET.SND_CWND] ;
jl @f ;
mov ecx, [eax + TCP_SOCKET.SND_CWND] ;
@@: ;
call TCP_outflags ; flags in dl
;------------------------
; data being forced out ?
; If in persist timeout with window of 0, send 1 byte.
; Otherwise, if window is small but nonzero, and timer expired,
; we will send what we can and go to transmit state
test [eax + TCP_SOCKET.t_force], -1
jz .no_force
test ecx, ecx
jnz .no_zero_window
cmp ebx, [eax + STREAM_SOCKET.snd + RING_BUFFER.size]
jge @f
and dl, not (TH_FIN) ; clear the FIN flag ??? how can it be set before?
@@:
inc ecx
jmp .no_force
.no_zero_window:
mov [eax + TCP_SOCKET.timer_persist], 0
mov [eax + TCP_SOCKET.t_rxtshift], 0
.no_force:
;--------------------------------
; Calculate how much data to send (106)
mov esi, [eax + STREAM_SOCKET.snd + RING_BUFFER.size]
cmp esi, ecx
jl @f
mov esi, ecx
@@:
sub esi, ebx
;------------------------
; check for window shrink (107)
; If FIN has been set, but not ACKed, but we havent been called to retransmit, esi will be -1
; Otherwise, window shrank after we sent into it.
jnc .bigger_than_zero
; enter persist state
xor esi, esi
; If window shrank to 0
test ecx, ecx
jnz @f
; cancel pending retransmit
mov [eax + TCP_SOCKET.timer_retransmission], 0
; pull SND_NXT back to (closed) window, We will enter persist state below.
push [eax + TCP_SOCKET.SND_UNA]
pop [eax + TCP_SOCKET.SND_NXT]
@@:
; If window didn't close completely, just wait for an ACK
.bigger_than_zero:
;---------------------------
; Send one segment at a time (124)
cmp esi, [eax + TCP_SOCKET.t_maxseg]
jle @f
mov esi, [eax + TCP_SOCKET.t_maxseg]
;;; sendalot = 1
@@:
;--------------------------------------------
; Turn of FIN flag if send buffer not emptied (128)
mov edi, [eax + TCP_SOCKET.SND_NXT]
add edi, esi
sub edi, [eax + TCP_SOCKET.SND_UNA]
sub edi, [eax + STREAM_SOCKET.snd + RING_BUFFER.size]
cmp edi, 0
jge @f
and dl, not (TH_FIN)
@@:
;-------------------------------
; calculate window advertisement (130)
mov ecx, SOCKET_MAXDATA
sub ecx, [eax + STREAM_SOCKET.rcv + RING_BUFFER.size]
;------------------------------
; Sender silly window avoidance (131)
test esi, esi
jz .len_zero
cmp esi, [eax + TCP_SOCKET.t_maxseg]
je .send
;;; if (idle or TF_NODELAY) && (esi + ebx >= so_snd.sb_cc), send
test [eax + TCP_SOCKET.t_force], -1 ;;;
jnz .send
mov ebx, [eax + TCP_SOCKET.max_sndwnd]
shr ebx, 1
cmp esi, ebx
jge .send
mov ebx, [eax + TCP_SOCKET.SND_NXT]
cmp ebx, [eax + TCP_SOCKET.SND_MAX]
jl .send
.len_zero:
;----------------------------------------
; Check if a window update should be sent (154)
test ecx, ecx
jz .no_window
;;; TODO 167-172
.no_window:
;--------------------------
; Should a segment be sent? (174)
test [eax + TCP_SOCKET.t_flags], TF_ACKNOW ; we need to ACK
jnz .send
test dl, TH_SYN + TH_RST ; we need to send a SYN or RST
jnz .send
mov ebx, [eax + TCP_SOCKET.SND_UP] ; when urgent pointer is beyond start of send bufer
cmp ebx, [eax + TCP_SOCKET.SND_UNA]
jg .send
test dl, TH_FIN
jz .enter_persist ; no reason to send, enter persist state
; FIN was set, only send if not already sent, or on retransmit
test [eax + TCP_SOCKET.t_flags], TF_SENTFIN
jnz .send
mov ebx, [eax + TCP_SOCKET.SND_NXT]
cmp ebx, [eax + TCP_SOCKET.SND_UNA]
je .send
;--------------------
; Enter persist state (191)
.enter_persist:
DEBUGF 1,"Entering persist state\n"
;;; 213 - 217
;----------------------------
; No reason to send a segment (219)
DEBUGF 1,"No reason to send a segment\n"
mov [eax + SOCKET.lock], 0
ret
;-----------------------------------------------
;
; Send a segment (222)
;
; eax = socket pointer
; esi = data len
; dl = flags
;
;-----------------------------------------------
.send:
DEBUGF 1,"Preparing to send a segment\n"
mov edi, TCP_segment.Data ; edi will contain headersize
sub esp, 8 ; create some space on stack
push eax ; save socket pointer
;------------------------------------
; Send options with first SYN segment
test dl, TH_SYN
jz .options_done
push [eax + TCP_SOCKET.ISS]
pop [eax + TCP_SOCKET.SND_NXT]
test [eax + TCP_SOCKET.t_flags], TF_NOOPT
jnz .options_done
mov ecx, 1460
or ecx, TCP_OPT_MAXSEG shl 24 + 4 shl 16
bswap ecx
push ecx
add di, 4
test [eax + TCP_SOCKET.t_flags], TF_REQ_SCALE
jz .no_syn
test dl, TH_ACK
jnz .scale_opt
test [eax + TCP_SOCKET.t_flags], TF_RCVD_SCALE
jz .no_syn
.scale_opt:
movzx ecx, byte [eax + TCP_SOCKET.request_r_scale]
or ecx, TCP_OPT_WINDOW shl 24 + 4 shl 16 + TCP_OPT_NOP shl 8
bswap ecx
pushd ecx
add di, 4
.no_syn:
;------------------------------------
; Make the timestamp option if needed
test [eax + TCP_SOCKET.t_flags], TF_REQ_TSTMP
jz .no_timestamp
test dl, TH_RST
jnz .no_timestamp
test dl, TH_ACK
jz .timestamp
test [eax + TCP_SOCKET.t_flags], TF_RCVD_TSTMP
jz .no_timestamp
.timestamp:
mov ebx, [timer_ticks]
bswap ebx
push ebx
pushw 0
pushd TCP_OPT_TIMESTAMP + 10 shl 8 + TCP_OPT_NOP shl 16 + TCP_OPT_NOP shl 24
add di, 10
.no_timestamp:
; <Add additional options here>
.options_done:
; eax = socket ptr
; edx = flags
; edi = header size
; esi = data len
;---------------------------------------------
; check if we dont exceed the max segment size (270)
add esi, edi ; total TCP segment size
cmp esi, [eax + TCP_SOCKET.t_maxseg]
jle .no_overflow
mov esi, [eax + TCP_SOCKET.t_maxseg]
;;; sendalot = 1
.no_overflow:
;-----------------------------------------------------------------
; Start by pushing all TCP header values in reverse order on stack
; (essentially, creating the tcp header on the stack!)
pushw 0 ; .UrgentPointer dw ?
pushw 0 ; .Checksum dw ?
pushw 0x00a0 ; .Window dw ? ;;;;;;;
shl edi, 2 ; .DataOffset db ? only 4 left-most bits
shl dx, 8
or dx, di ; .Flags db ?
pushw dx
shr edi, 2 ; .DataOffset db ? ;;;;
push [eax + TCP_SOCKET.RCV_NXT] ; .AckNumber dd ?
ntohd [esp]
push [eax + TCP_SOCKET.SND_NXT] ; .SequenceNumber dd ?
ntohd [esp]
push [eax + TCP_SOCKET.RemotePort] ; .DestinationPort dw ?
ntohw [esp]
push [eax + TCP_SOCKET.LocalPort] ; .SourcePort dw ?
ntohw [esp]
push edi ; header size
;---------------------
; Create the IP packet
mov ecx, esi
mov ebx, [eax + IP_SOCKET.LocalIP] ; source ip
mov eax, [eax + IP_SOCKET.RemoteIP] ; dest ip
mov di, IP_PROTO_TCP shl 8 + 128
call IPv4_output
jz .fail
;-----------------------------------------
; Move TCP header from stack to TCP packet
push ecx
mov ecx, [esp+4]
lea esi, [esp+4+4]
shr ecx, 2
rep movsd
pop ecx ; full TCP packet size
pop esi ; headersize
add esp, esi
mov [esp + 4], eax ; packet ptr
mov [esp + 4+4], edx ; packet size
mov edx, edi ; begin of data
sub edx, esi ; begin of packet (edi = begin of data)
push ecx
sub ecx, esi ; data size
;--------------
; Copy the data
; eax = ptr to ring struct
; ecx = buffer size
; edi = ptr to buffer
mov eax, [esp+4] ; get socket ptr
add [eax + TCP_SOCKET.SND_NXT], ecx ; update sequence number
add eax, STREAM_SOCKET.snd
push edx
call SOCKET_ring_read
pop esi ; begin of data
pop ecx ; full packet size
pop eax ; socket ptr
;----------------------------------
; update sequence number and timers (400)
test [esi + TCP_segment.Flags], TH_SYN + TH_FIN
jz @f
inc [eax + TCP_SOCKET.SND_NXT] ; syn and fin take a sequence number
test [esi + TCP_segment.Flags], TH_FIN
jz @f
or [eax + TCP_SOCKET.t_flags], TF_SENTFIN ; if we sent a fin, set the sentfin flag
@@:
mov edx, [eax + TCP_SOCKET.SND_NXT]
cmp edx, [eax + TCP_SOCKET.SND_MAX]
jle @f
mov [eax + TCP_SOCKET.SND_MAX], edx
;;;; TODO: time transmission (420)
@@:
; set retransmission timer if not already set, and not doing an ACK or keepalive probe
cmp [eax + TCP_SOCKET.timer_retransmission], 1000 ;;;;
jl .retransmit_set
cmp edx, [eax + TCP_SOCKET.SND_UNA] ; edx = [eax + TCP_SOCKET.SND_NXT]
je .retransmit_set
mov edx, [eax + TCP_SOCKET.t_rxtcur]
mov [eax + TCP_SOCKET.timer_retransmission], dx
mov [eax + TCP_SOCKET.timer_persist], 0
mov [eax + TCP_SOCKET.t_rxtshift], 0 ;;; TODO: only do this if timer_persist was set
.retransmit_set:
;--------------------
; Create the checksum
DEBUGF 1,"checksum: ptr=%x size=%u\n", esi, ecx
TCP_checksum (eax + IP_SOCKET.LocalIP), (eax + IP_SOCKET.RemoteIP)
mov [esi+TCP_segment.Checksum], dx
; unlock socket
mov [eax + SOCKET.lock], 0
;----------------
; Send the packet
DEBUGF 1,"Sending TCP Packet to device %x\n", ebx
call [ebx + NET_DEVICE.transmit]
ret
.fail:
pop ecx
add esp, ecx
add esp, 4+8
mov [eax + SOCKET.lock], 0
DEBUGF 1,"TCP_output: failed\n"
ret